This thread (pun intended) is to document the most common, Honda thread size and fastener dimensions. I originally posted this forever ago, but figured I would revise the first post in this thread with updated information. If you wish to read the original contents of this post, which were last edited March 6th, 2007 (almost EXACTLY 15 years ago!) - here are the original, original post contents:

In general, Honda uses about 4-5 different sized threads. Honda fasteners are technically "flange head socket cap screws". Almost all of them are metric grade 10/10.9. Some are even Metric grade 12.9.

Note, when most mechanics say "remove five, 14mm bolts". When they say this, they are referring to 5 bolts which they need to use a 14mm socket on. The part that is actually 14mm is the "head" of the bolt.
When hardware stores, fastener retailers, engineers, etc refer to "14mm bolts", what they are referring to are bolts that have a thread or bolt diameter of 14mm.

M6x1.0 - most 10mm head bolts.
M8x1.25 - most 12mm head bolts.
M10x1.25 - most 14mm head bolts.
M12x1.25 - most 17mm head bolts.
M14x1.5 - most 19mm head bolts (but these can also be 17mm)
M16x1.5 - can have 19mm, 21mm, or 22mm heads?

Honda rarely deviates from these thread pitches, except for fasteners such as differential ring gear bolts, connecting rod bolts -- and other fasteners that are internal to the engine/drive train.
There are also some things that are deliberately abnormal, such as the bolts that are used on the steering column knuckle. I've seen where those are M11x1.25. -- Which is VERY similar to 7/16-20. Be careful not to mix these up.


Here are links to McMaster-Carr for various nuts that I have found in their catalog that match what Honda uses. They are Grade 10 / 10.9, flanged, and importantly, they have the same size head that Honda uses. None of that "13mm socket" on M8x1.25 crap. Ugh, so annoying! lol. I have also selected ones that are zinc plated.

Flange Nuts
M6x1.0 - 10mm - https://www.mcmaster.com/95108A104
M8x1.25 - 12mm - https://www.mcmaster.com/95108A105
M10x1.25 - 14mm - https://www.mcmaster.com/95108A103/
M12x1.25 - 17mm - https://www.mcmaster.com/95108A107/
M14x1.5 - 21mm - https://www.mcmaster.com/95003A214
M14x1.5 - 22mm - https://www.mcmaster.com/4391N117 (note: non-flange)

Obviously, these aren't the only possible options. Additionally, you should know that Honda uses distorted thread lock nuts for things like suspension fork bolts, sway bar end links. These distorted thread nuts are ones that Honda typically says to replace in the service manual. Here are links to McMaster-Carr where you can purchase equivalent, distorted thread lock nuts.

Distorted thread lock nuts:
M6x1.0 - 10mm - https://www.mcmaster.com/3528N11/
M8x1.25 - 13mm - https://www.mcmaster.com/3528N12/ - Ugh, annoying 13mm head.
M10x1.25 - 17mm - https://www.mcmaster.com/99183A480/ - M10x1.25 is normally 14mm head. However, 17mm is still common bolt head size, so I am deeming these permissible.
M12x1.25 - 19mm - https://www.mcmaster.com/99183A380/ - M12x1.25 is normally 17mm head. However, 19mm is still common bolt head size, so I am also deeming these permissible.

Stainless washers:
M6 - https://www.mcmaster.com/98690A113
M8 - https://www.mcmaster.com/98689A116
M10 - https://www.mcmaster.com/98689A117
M12 - https://www.mcmaster.com/98689A118/

Stainless fender (larger OD) washers:
M6 - https://www.mcmaster.com/91116A150
M8 - https://www.mcmaster.com/91116A160
M10 - https://www.mcmaster.com/91100A170
M12 - https://www.mcmaster.com/97310A134

Suggestions, questions, corrections are encouraged.


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Edit: 20220705_0541 EST - Fixing Flange Nut URLS
Edit: 20220727_1703 EST - Adding Pictures

 

M12 x 1.25 - rear inner seat rail bolt

 

I have no clue about any of the bolts, considering this is my first Honda, and I've only had it about 2 months. However this could come in real handy, sticky please?

 

D-series head stud thread: M10x1.25

B-series head stud thread: M11x1.5

 

 

rad

 

i don't know if this thread is relevant to what you're trying to accomplish, but it's definitely some info that might help some people looking for

a few TURBO thread pitches
https://honda-tech.com/zerothread?id=373905

 

Common:
M10x1.5 - Shifter (for all you poor saps that need a locknut for your Type-R ****)

 

up for more

 

bense...your correct....oil pan 14X1.5

 

anyone know the thread pitch of the bolts that hold down the cam caps on a b-series?

 

Actually the most common 10mm bolt is 6mm thread pitch.
On a 92-95 anyway.
I use that size chaser the most.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ReDemoN &raquo;</TD></TR><TR><TD CLASS="quote">Actually the most common 10mm bolt is 6mm thread pitch.
On a 92-95 anyway.
I use that size chaser the most.</TD></TR></TABLE>

you caught me before I could edit it

I believe that most of our M8-1.25 bolts are what we use the 12mm sockets for. However most of the nuts/bolts that we buy in conventional hardware stores that are M8-1.25 use 13mm heads. I just need to verify that 1.25 is the common thread pitch.

 

keep em coming guys

 

.

 

m8-1.25 is our common honda bolt with the 12mm head

 

I cant remember them off the top of my head and dont have the time right now but when i get home from class ill look some up. Cause there are "custom" ones for special things (like LS/VTEC, oil spuirters, etc). Those use a NPT thread to cover or tap. But when i get home ill check it.

Also i believe the crank pully is the M16 x .5 pitch and the flywheels are 14 x .5 But dont quote me just yet ill be back for for sures if no one checked it.

 

thanks Luserkid

 

Sorry i lagged but schools been killer. Heres some not so common thread pitches that hondas have and if you ever screw them up is hard to find, so it better to have the correct pitch numbers then send out a stripped bolt asking "can you figure out the thread pitch"

Flywheel bolts (B and D the same, dont know about H and K): M12 x 1.0
Pressure Plate bolts (same b and d dont know about h and k): M8 x 1.25
Oil pan/Trans drain plug: M14 x 1.5
Trans case bolts that hold that little ball bearing in place with spring: M12 x 1.0 (oddly enough this is a hard tap to find, and timesert hasnt even made an insert for it yet so dont screw this one up)
Oil Pressure Sensor (back of block): 1/8 - 28BSP
Bumper screw/bolts: M6 x 1.0
Crank Bolt: M14 x 1.25
14mm Allen Bolt: M28 x 1.5
10mm Allen Bolt: M20 x 1.0
19mm bolt that connects rear trans bracket to trans: M14 x 1.5

If theres any other bolts that people would like to know let me know and ill get you the pitch.

 

thanks for the post Luserkid

 

m16 is for the thermoswitch, under the water pipe. i never tried a crank pulley bolt to see if it fits.

 

sticky this

 

Would anyone happen to know the specs on the hood hinge bolts? Im going to be machining up a few hood spacers, and would like to know this. Thanks!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vestalfootball72 &raquo;</TD></TR><TR><TD CLASS="quote">Would anyone happen to know the specs on the hood hinge bolts? Im going to be machining up a few hood spacers, and would like to know this. Thanks!</TD></TR></TABLE>

im thinking:
M8-1.25 (common) (probably most of our 12mm head bolts)

 

exhaust header/ cat studs... i cant remember M12x 1.25?